Prior to the present invention, efforts have been made to produce cartridge blanks typically for the military firearms such as M1, M2 and the like, which will remain stable and fireable over prolonged periods of shelf-life. However, prior to the present invention there has been no outstanding success in such achievement, as a result of differences in the coefficient of expansion in the cartridge and the open-end of the shell mounted thereon, moisture making its way inevitably into the envelope space such that the cartridge assembly often will not fire after shelf life of varying lengths of time, thus being totally unreliable. The military uses large quantities of such blanks and has found such difficulties and problems very frustrating in and for their training excercises. Until the present invention, the above-noted problems have appeared to defy solution.